Dialysis Patients with Hyperphosphatemia May Benefit from Magnesium

Dialysis is a process for removing waste and excess water from the blood, and is used primarily as an artificial replacement for lost kidney function in people with kidney failure.

When your kidneys fail, dialysis keeps your body in balance by:

removing waste, salt and extra water to prevent them from building up in the body
keeping a safe level of certain chemicals in your blood, such as potassium, sodium and bicarbonate
helping to control blood pressure

Achieving and maintaining higher magnesium levels may improve the cardiovascular prognosis of hemodialysis (HD) patients, according to a new study.

Increasing magnesium may be another strategy to reduce phosphate load, which has been linked to cardiovascular disease. Conventional therapies, such as dietary restriction and dialysis, have been only moderately effective at controlling phosphate levels.

“In accordance with the recent in vitro studies showing the protective role of Mg on phosphate-induced calcifications of [vascular smooth muscle cells], we found that the mortality risk of patients with hyperphosphatemia was significantly attenuated with increasing serum Mg levels,” stated Yoshitaka Isaka, MD, of Osaka University Graduate School of Medicine in Japan and colleagues in PLOS One.

As high serum magnesium potentially carries risks, such as oversuppression of parathyroid hormone, patient magnesium levels would need to be monitored, according to the researchers.

For the study, the investigators analyzed data from more than 142,000 HD patients in the Renal Data Registry of the Japanese Society for Dialysis Therapy in 2009. They categorized patients into 3 groups by serum magnesium levels: the lower group had less than 2.7 mg/dL magnesium; intermediate had 2.7 to less than 3.1 mg/dL; and higher had 3.1 mg/dL or more.

Within a year, 11,401 patients died, 41.7% from cardiovascular disease. An increase in serum phosphate levels increased the risk of cardiovascular mortality in patients in the low- and intermediate- magnesium groups, whereas no significant risk was observed in the higher-magnesium group. Among patients with serum phosphate levels of 6 mg/dL or more, the risk of cardiovascular mortality significantly decreased as serum magnesium levels rose.

Magnesium deficiency is known to be involved in cardiovascular disease. Several studies likewise show that sufficient magnesium has favorable effects on vascular function.

The researchers suggest several possible ways to increase magnesium in dialysis patients with hyperphosphatemia: increase the dialysate magnesium level and prescribe magnesium-containing phosphate binders. Increasing dietary magnesium seems impractical for patients with end-stage renal disease. Additional research on the safety of these steps is needed before they could be implemented.